1. Field of the Invention
This invention relates to the vapor phase oxidation of acetaldehyde to peracetic acid, acetic acid being also formed at the same time.
2. Description of the Prior Art
A vapor phase process for producing peracetic acid by reacting acetaldehyde with oxygen at up to 232.degree. C. and pressures up to 50 pounds per square inch was disclosed by Bludworth in U.S. Pat. No. 2,314,383, Mar. 23, 1943. More recently it has been suggested to feed acetaldehyde and oxygen to a heated aluminum reactor and pass the gaseous reaction products to a fractionating column to rapidly separate peracetic acid from unreacted acetaldehyde and acetic acid.
The known vapor phase reactors contain, as an essential element, a fan, blower or other stirrer capable of creating vigorous mixing throughout the entire reactor volume. This type of reactor, used by Bludworth and others, is properly termed a steady-state backmix flow reactor.
Bludworth disclosed producing 6.65 parts of peracetic acid by weight per minute or 400 parts per hour while recycling through the backmix blower, in the reactor loop, 170 parts per minute or 10,000 parts per hour of hot reaction gases. To produce 400 pounds of product peracetic acid per hour required recycling over 5 tons of hot recycle gases per hour against pressure and within the confines of a reactor loop. The blower employed in such a process obviously has to be large and efficient. Blower failure in these fan-type, back-mix, reactors results in an explosion which is the reason why the vapor phase process has not been used commercially. A successful blower has to be large and capable of withstanding an explosion which makes the blower economically undesirable in terms high initial cost and expense of operation.
Though the theoretical stoichiometric ratio of acetaldehyde to oxygen in the vapor phase process is 1:1, Bludworth disclosed acetaldehyde to oxygen ratios of at least 8:1. British Pat. No. 927,053, published 20 years after Bludworth, May 22, 1963, claimed an improved overall acetaldehyde to oxygen ratio of about 5 to 1. This British patent divided the Bludworth reaction between two reactors, the first reactor containing as "an essential element an efficient fan or blower capable of creating vigorous mixing throughout the entire reactor volume".
It is the principal object of this invention to provide a vapor phase process for oxidizing acetaldehyde to peracetic acid that can be operated without using a steady-state back-mix flow reactor, and which can use low acetaldehyde to oxygen ratios so costs are minimized, and in which danger of explosion is reduced to an acceptable level.